(1) Field of the Invention
The present invention relates to an image reading device for reading image information from originals and an image forming apparatus equipped with the image reading device, in particular, relating to an image reading device with a multiple number of document trays and a multi-functional digital image forming apparatus having copier, facsimile and other functions.
(2) Description of the Prior Art
Conventionally, there have been developed multi-functional digital image forming apparatus which can implement multiple functions such as copier and facsimile functions. In such an image forming apparatus, image information need to be read from originals in either of the copier and facsimile functions. Therefore, recently, image reading devices equipped with an automatic document feeder have been often used in order to make the reading operation smooth and efficient.
As an example of technology relating to the image reading device as above, Japanese Patent Application Laid-Open Hei 6 No. 276350 can be mentioned. This technical publication discloses an automatic document feeder having a multiple number of document trays corresponding to copier and facsimile functions, respectively, so as to selectively perform copying operation of documents and facsimile transmission of documents depending upon the operational status.
However, the above prior art, i.e., the multi-functional image forming apparatus is mainly aimed at avoiding mis-operations along with implementation of the copier or facsimile function, so only presents a limited improvement in operativity as a multi-functional machine including an image reading device.
Since, in typical or most multi-functional machines, the originals to be read during copier reading document have been adapted to be set facing in a reverse direction to that for facsimile, mis-operations would be liable to often occur if the machine has only one document tray. In order to avoid this problem, a separate document tray is provided for each function.
In the above art, however, since the operation of the multi-functional machine is automatically selected after detecting whether each document tray has documents thereon, the user's wish cannot be sufficiently satisfied when documents are scanned.
There is no reference or consideration of the point whereby the conditions for each document tray may be set or modified taking the advantage of multiple document trays and the operational control of the machine may be adapted to be designated based on the conditions.